1. Technical Field
This invention relates to sealed, blow molded aseptic containers and to a method and apparatus for forming such containers.
2. Description of Known Technology
The production of aseptic containers requires that parisons be blown with high pressure sterile blow air, vented and, when the containers will not be immediately filled (as is typically the case), sealed to preserve the sterility of the empty container's interior. One problem with blow molding such containers is that, after sealing, the plastic of the bottle cools and shrinks. This may also result in a warming of the air within the container. As container shrinks, the volume of trapped air within the container does not. This can cause deformation in the shape of the container, particularly its side walls. If the air within the container warms and thus expands, the deformation in the shape of the container can be further exacerbated.
To prevent the causes of deformation, the volume or pressure of the air remaining in the container at the time of sealing must be reduced. Known systems have evacuated the blow air out of the container prior to sealing by using a vacuum. The vacuum can be obtained by using a vacuum pump connected to the interior of the container or by using a venturi, with its low pressure inlet port connected to the interior of the container.
As seen from the above, there exists a need for a simplified method and apparatus to evacuate the blow air from the containers prior to sealing, which would eliminate the need to use a vacuum and/or venturi.